Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 261828
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
228 PM EDT FRI MAY 26 2017


PRELIM DAY 1 QPF DISCUSSION
VALID MAY 27/0000 UTC THRU MAY 28/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1...

...FRONT RANGE OF WY/CO...CENTRAL PLAINS TO MID-LOWER MS VALLEY...

WATER VAPOR SHOWS A CIRCULATION DEVELOPING IN SOUTHERN ID.  AS THE
CIRCULATION MOVES EAST THROUGH TONIGHT TOWARDS WY...THE ASCENT
CAUSED BY STEEPENING 700-500 MB LAPSE RATES AND STRENGTHENING
DIVERGENCE ALOFT TRIGGERS SHOWERS/STORMS ACROSS WY AND NORTHERN CO
 THAT MOVE DOWNSTREAM ACROSS THE PLAINS OF NE AND AND NORTHWEST
KS. AS PW VALUES CLIMB TO NEAR 1.25 " INTO NORTHWEST KS...ENHANCED
LOW LEVEL CONVERGENCE OCCURS ON THE NOSE OF THE LOW LEVEL
JET...FAVORING AN INCREASE IN SHOWERS/STORMS EXITING NORTHEAST CO
ACROSS NORTHWEST KS.
MANY PIECES OF GUIDANCE...PARTICULARLY HIGH-RES/CAMS... CONTINUE
TO SHOW A BI-MODAL DISTRIBUTION WITH THE QPF (2 DISTINCT
MAXIMA)...ONE ACROSS NORTHEAST CO EASTWARD INTO SOUTHWEST
NE-NORTHWEST KS (BETTER THERMODYNAMICS) WITH ANOTHER FARTHER NORTH
ACROSS SOUTHEAST WY EASTWARD INTO WESTERN NE (BETTER DYNAMICS).
WPC CONTINUED WITH THIS IDEA WHEN COMPOSING THE QPF...LEANING
TOWARD THE HIGH-RES MODELS WITH THE LOCATION/AMOUNTS WITH THE
SOUTHERN AXIS...WHILE ENCOMPASSING A WIDER ARRAY OF GUIDANCE
FARTHER NORTH

MOST MODELS/HIGH RES ENSEMBLES HAVE THIS ACTIVITY OVERNIGHT BUT
SPLIT AS TO ITS EVOLUTION ON SAT...WITH THE NAM CONUS NEST AND
UKMET PROVIDING SPATIAL CONTINUITY VS THE DRIER OPERATIONAL
GFS/PARENT NAM/WRF ARW WHICH SHOW A RELATIVE MINIMA SAT MORNING.
THE WETTER MODELS WERE PREFERRED TO KEEP QPF CONTINUITY.

SAT AFTERNOON THE MODELS SHOW THE 850-700 MB FRONT DEVELOPING AND
MOVING EAST ACROSS THE CENTRAL PLAINS.  STRONG LOW LEVEL
CONVERGENCE IN ADVANCE OF THE WAVE AND WAR/MOISTURE ADVECTION
SUPPORT AN INCREASE IN SHOWER/STORM ACTIVITY FROM NORTHEAST KS AND
MUCH OF MO. THE GFS FORECASTS HEAVIER AMOUNT NORTH INTO THE LESS
UNSTABLE AIR IN IOWA AND THIS WAS LESS FAVORED...AS MOST
CONVECTIVE EVENTS RESULT IN LIGHTER AMOUNTS FURTHER DOWNSTREAM IN
A LESS UNSTABLE AIRMASS. MANUAL PROGS BLENDED THE 12Z NAM/CANADIAN
REGIONAL GEM/00Z ECMWF/12Z UKMET/12Z WRF FROM NSSL SAT AFTERNOON.


...OHIO VALLEY/GREAT LAKES/CENTRAL APPALACHIANS/MID ATLANTIC...

THE MODELS FORECAST A CLUSTER OF SHOWERS/STORMS IN IL THIS
AFTERNOON TO PERSIST AND MOVE DOWNSTREAM ACROSS THE OH VALLEY AND
CENTRAL APPALACHIANS TONIGHT AND INTO THE MID ATLANTIC STATES
TOMORROW.
THE GFS REMAINS ON THE NORTHERN EDGE OF THE SUITE OF GUIDANCE WITH
RESPECT TO THE QPF AXIS ACROSS THE GREAT LAKES TONIGHT. THE OTHER
MODELS ARE FURTHER SOUTH INTO THE FORECAST AXIS OF INSTABILITY AND
REMAIN PREFERRED.
THE HIGH-RES CONVECTIVE ALLOWING MODELS
(RGEM...WRF-ARW...NMMB...AND NSSL WRF) ARE PROBABLY TOO HEAVY WITH
THEIR HIGHEST AMOUNTS GIVEN THE SHORT DURATION PLUS FAIRLY MODEST
STRENGTH OF LOW LEVEL INFLOW INTO THE DEVELOPING ACTIVITY.
ACTIVITY TYPICALLY DEVELOPS INTO THE AXIS OF THE HIGHER AVAILABLE
MOISTURE AND LOW LEVEL JET...WHICH IN THE GFS IS IN INDIANA(GFS
HIGHEST QPF IS IN MI)...WHICH WOULD BRING IT INTO BETTER AGREEMENT
WITH THE OTHER MODELS DEVELOPING ACTIVITY FURTHER SOUTH.

WPCQPF WAS FAIRLY CLOSE TO A BLEND OF THE 12Z UKMET/00Z ECMWF/THE
12Z NCEP RENDITION OF THE NSSL WRF ARW...WITH CONTINUED
AREAL-AVERAGE TOTALS BETWEEN 0.50-1.0 INCH. GIVEN THE WET
ANTECEDENT SOILS/LOW FFG VALUES IN THE OH VALLEY FROM THE MID WEEK
RAINFALL...THE AREA WILL NEED TO BE MONITORED FOR EXCESSIVE
RAINFALL IN CASE HEAVIER RAINS DO DEVELOP.

THE 12Z NAM AND 00Z ECMWF ARE FASTER WITH THE 700 MB WAVE TIMING
THAN THE 12Z GFS/GEFS MEAN...ADDING ANOTHER DIMENSION TO THE
UNCERTAINTY.  THE CANADIAN REGIONAL GEM LIKES THE IDEA OF
CONVECTION DEVELOPING FURTHER SOUTH INTO TN INTO VA DURING THE DAY
SAT.  THE 12Z NAM SHOWS THE PRECIPITATE WATER MAXIMA IN THESE
AREAS SAT ALONG WITH 700 MB CONVERGENCE MAXIMA SO THE IDEA WAS
ADOPTED.

PETERSEN


GRAPHICS AVAILABLE ON THE WEB AT WWW.WPC.NCEP.NOAA.GOV


24HR QP VT 28/00Z
 0.01 565902 565885 562870 557842 550818 546806 539796 534792
      527788 524786 521784 520781 518771 509752 505745 500737
      486725 482724 480726 478725 472728 469731 470784 468794
      467799 467803 467810 466815 467828 455872 447878 437876
      434874 431870 429866 428859 421803 420792 423783 423779
      421774 419764 420757 423758 423763 428770 431773 434773
      435768 433764 420750 417740 414734 411731 407730 404733
      404740 404744 402745 398745 396743 395740 392740 387739
      382740 378741 375740 369740 366743 359747 355751 353756
      352764 352770 351774 351780 350785 348796 346822 344832
      343838 342843 342869 343877 344882 345890 345895 344899
      333913 323926 323932 321937 321941 323946 329947 334949
      333952 320966 315973 313977 312984 313996 319997 324997
      333992 340984 348979 355976 358973 362972 366972 368974
      369979 368986 367990 366997 365007 363012 362018 361023
      360032 362042 374056 376060 374065 373071 373076 374083
      374091 379099 385094 392098 390105 387109 381113 379117
      380119 383118 382123 381125 382128 385129 387128 388131
      386136 386141 391145 393140 395134 395128 394122 393117
      396113 402116 408117 417114 424134 427139 429139 430131
      434126 439122 445114 448113 451109 453105 452101 445087
      441083 443080 446080 449083 455084 459087 464087 468085
      470083 467077 461076 453071 451069 450066 449058 450051
      451046 452039 454034 454021 452009 451005 452001 453992
      455972 443963 438963 434963 433961 431956 433951 437942
      439938 439930 440922 440914 441910 443911 447916 450918
      453923 462923 471922 474921 477920 482922 481928 480932
      477937 474946 470957 467967 467976 465981 465008
 0.01 465008 466014 466019 467026 474036 477040 483043 488043
      492041 494039 495041 495046 495051 496055 498059 504060
      515056 524052 534048 542041 544035 546027 543014 538999
      534987 529972 528966 530963 531957 535952 538944 542931
      546927 549926 552928 556930 561930 563925 564916 564907
      565902
 0.01 510986 510981 509978 507973 505970 504965 501963 499965
      496965 492968 491971 492974 495977 499980 501983 504985
      508988 510986
 0.01 485643 485638 483633 479632 472633 466636 455642 450647
      448652 444657 442664 443672 446678 450682 453679 459675
      465673 476667 481655 484649 485643
 0.01 483133 481130 480129 478126 475124 473123 470122 468122
      466124 466127 469128 471131 474132 477134 479135 481133
      483133
 0.01 490980 490977 489975 488977 488980 489982 490980
 0.01 386201 385196 382193 378190 375188 371185 366182 363181
      362186 366188 369191 372194 375197 378199 384201 386201
 0.01 382022 381020 380019 379018 377018 377017 376016 374015
      373015 372013 370013 369014 370016 371017 372018 373019
      374020 375020 377021 377022 379023 381023 382022
 0.01 340943 341941 339940 338941 338943 339945 340943
 0.01 300023 300019 296018 293019 289018 281016 278015 274015
      268017 263023 266027 271032 279033 288033 294030 298025
      300023
 0.01 263805 263802 261799 259797 257796 255797 254802 252803
      251806 252810 254812 257813 258811 260807 262807 263805
 0.01 241839 241837 240837 239835 238834 237834 236833 234833
      234834 233835 232836 231837 230838 230840 231842 232843
      233844 233845 235845 237845 239844 239843 240841 240840
      241839
 0.25 551892 551886 550882 547875 541861 534848 528836 520824
      518821 515821 514824 514830 520845 526859 533872 538886
      543893 546895 551892
 0.25 517915 518913 517912 515911 513911 512911 510912 508913
      510915 512916 513917 515917 517916 517915
 0.25 443072 440061 439049 438043 441039 442034 440028 440002
      439997 437995 432993 427993 422992 419989 415980 416976
      418971 420966 420957 419948 416944 414942 410940 407935
      403929 398920 393912 387904 380898 379889 380878 380872
      381867 382857 381851 381846 383842 385847 386852 388851
      393862 396870 400876 405875 408873 410868 411863 411848
      412837 412823 409811 407801 406796 404792 399786 396783
      390783 386787 385792 384803 382814 379818 377819 375818
      371815 367813 363815 358823 356830 354842 353854 352866
      352878 352890 353900 354906 355911 359918 362929 366938
      377954 379957 381961 385970 391986 390991 387995 385000
      386007 389017 390022 390031 390036 388040 384041 382039
      376033 374031 371032 371037 375045 380051 386052 391054
      400059 402061 402066 404070 407074 411076 415076 418074
      422072 426073 428075 432077 434074 439072 443072
 0.25 406047 407044 406042 405042 404042 403044 404045 406047
      406047
 0.25 376778 376774 374769 374767 372763 370762 367763 365764
      364769 365773 366777 367780 369782 371783 373783 375781
      376778
 0.25 337976 337975 337973 336971 335971 334971 332973 331973
      330974 329975 328977 327980 328981 330981 332981 333980
      334980 335979 336978 337976 337976
 0.50 430025 429015 427005 425002 421003 419006 415005 414995
      412984 411976 412967 412958 412952 410948 405943 401938
      391924 384913 380910 376911 373913 371917 371921 371925
      375932 378941 383948 386954 390961 395980 394990 391997
      390002 391005 392011 392016 394034 397038 401037 407031
      414022 414028 413032 412037 412041 413045 417046 420046
      423044 428032 430025
 0.50 408850 407838 405824 402814 398807 394809 393814 392824
      391831 391838 394849 396861 398867 402869 405866 408861
      408850
 0.50 370882 369879 370873 369866 368861 366858 362858 359865
      358874 357883 356894 356897 358901 361903 364901 368894
      370885 370882
 1.00 421032 421029 421028 419028 419029 418031 419033 421032
      421032
 1.00 409017 410005 410995 409990 408987 405983 402984 401988
      400993 397002 396006 396011 396023 398030 401029 403026
      407020 409017
 1.00 402956 401947 398940 393933 389929 382925 381925 379929
      380935 382938 386944 390949 395956 400961 402956
 1.50 408014 408010 408005 409000 409996 408993 406990 403991
      402993 401998 401001 400005 400009 400014 401016 404016
      406016 408014

$$





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